FIG. 1 is a perspective view of an exemplary medical injection system 100 (the ACIST CVi® system) for delivering a contrast agent into a patient's vascular system for medical imaging. FIG. 1 illustrates a first fluid reservoir 132 for supplying a syringe-type positive displacement pump 130 of a pressurizing unit, via a fill tubing line 102, and an injection tubing line 104, which is coupled to pump 130 for injection of, for example, a radiopaque contrast agent, into a patient's vascular system via an inserted catheter (not shown) that may be coupled to a patient tubing line 122 at a connector 120 thereof. FIG. 1 further illustrates a second fluid reservoir 138 from which a diluent, such as saline, is drawn by a peristaltic pump 106 through yet another tubing line 128 that feeds into tubing line 122. A manifold valve 124 and associated sensor 114 control the flow of fluids into tubing line 122, from pump 130 and from tubing line 128.
Although not shown in FIG. 1, the syringe-type positive displacement pump of unit 130 includes a fill port and an injection port to which tubing lines 102 and 104, respectively are coupled. An apparatus that allows fluid to flow into pump 130, via fill tubing line 102, while blocking flow to injection tubing line 104, and then allows fluid to flow out from pump 130, via injection tubing line 104, while blocking flow to fill tubing line 104, is desired in order to prevent back flow through line 104 during filling, and back flow through line 102 during injection. Such an apparatus may be integrated into system 100 in the general area designated by reference numeral 125, and may be in the form of a stop cock-type manifold. Although various configurations of this type manifold apparatus are known in the art, there is a need for new and improved configurations of manifold assemblies for regulating flow paths in medical injection systems, for example, like system 100.